| 摘要 |
PURPOSE:To improve the durability, vacuum retaining capacity and adaptability to high speed, high precision linear and rotary movement of a shaft, by composing a multi-stage magnetic fluid seal in the axial direction round the movable shaft. CONSTITUTION:A bearing assembly 4, fixed to an opening 3 on a wall 1 of a vacuum chamber 1, had ball bearings 6 on both ends of a flanged cylindrical casing 5 for supporting a shaft movable in the X and Y direction shown by arrows. This vacuum seal is fitted between both bearings 6 in the casing 5 of bearing assembly 4, being composed of five disc yokes 11-15 and four cylindrical permanent magnets 16-19 alternately in series in the axial direction. Each yoke has annular magnetic poles 11a, 12a axially projected on the internal circumference, and the clearance between each magnetic pole and the shaft 7 is filled with magnetic fluid 22 mixed with fine magnetic particles. |
